Evidence of significant co-occurrence between pain and alcohol consumption are emerging. There is also indication that alcohol can induce acute analgesia with cross- sectional evidence that some individuals may be motivated to use alcohol to cope with pain. However, potential moderators and mechanisms of action remain largely uncharacterized and poorly understood. This proposal will focus on examining potential pharmacological and genetic mechanisms mediating the alcohol-pain connection using the mouse BXD recombinant inbred (RI) panel. The primary objective of this proposal is to identify novel genetic factors that contribute to alcohol acute analgesic effects and development of tolerance in mice. We observed for the first time strain differences between C57BL6/J and DBA/2J for alcohol-induced antinociceptive effects in the hot- plate test after oral administration. In Aim 1, we will examine and characterize alcohol?s analgesic properties in acute pain models after oral dosing in the mouse. In Aim 2, we will use BXD RI lines to map genomic regions, or QTLs, that are causally associated with susceptibility versus resilience to alcohol effects and the development of tolerance in the hot-plate test. In Aim 3, we will identify changes in the transcriptome associated with acute analgesic phenotype and tolerance of alcohol. We will measure changes in gene expression in relevant neuronal tissues (amygdala, periaqueductal grey and prefrontal cortex) associated with alcohol initial sensitivity and tolerance in extreme RI strains. In Aim 4, we will validate candidate quantitative trait genes and functional variants identified and ranked by Aims 2-3.